<form action="/register.html" method="post" id="need_redirect">
    <input type="hidden" name="username" value="<?=htmlentities($this->data['username'],ENT_QUOTES,"UTF-8")?>"/>
    <input type="hidden" name="fullname" value="<?=htmlentities($this->data['fio'],ENT_QUOTES,"UTF-8")?>"/>
    <input type="hidden" name="email" value="<?=htmlentities($this->data['email'],ENT_QUOTES,"UTF-8")?>"/>
    <input type="hidden" name="submitted" value="1"/>
</form>
<script type="text/javascript">
    document.getElementById("need_redirect").submit();
</script>